Regenerative air preheating



Dec. 26, -G. [SLEY REGENERATIVE AIR PREHEATING Filed Nov. 19, 1951 3 Sheets-Sheet frz/fm or @ZJ Hey ff? or Dec. 26,1933. G. H. lsLEY REGENERATIVE AIR PREHEATING Filed Nov. 19, 1931 3 Sheets-Sheet 2 Fwd 5 Sheets-Sheet 3 Filed Nov. 19. 1931 fn Uve/2z for regenerator 2', acquires, by passage through said regenerator, a very high temperature. A relatively small portion of this highly heated air, as shown by the broken line arrows in Fig. 1, flows through the conduit l and branch 5 to the burner 7, to support combustion of the fresh fuel supplied to said burner by the branch fuel pipe thus to give a high flame temperatureby the burning of said fuel; the balance of this highly heated air is conveyed through the pipe 1 to the station or stations, not shown, Where low grade fuel is being burned and where a high flame temperature is desired. The combustion products from the operative burner 7 pass downwardly in the chamber 3 of regenerator 2 and then upwardly in the chamber 3d of said regenerator, to which chambers they give up their heat before making exit, by way of branch connection 15 to the outlet opening 14 at the upper end of duct 13,-being directed into said outlet 14 by the valve 16 in the position of the latter shown by Fig. 1. Y l When the valves 16 and i7 are simultaneousl reversed, in the manner hereinafter described, all the air forced into the system by blower 11 is directed through branch 15 into the regenerator 2, and the combustion of fresh fuel for the regenerative preheating of the air supply transferred from the burner 7 to the burner 7. Under these conditions, it will be understood that the air in its passage through the previously-heated chainbers 3 and 3a of regenerator 2 will acquire the desired high temperature before making its exit, at the top of` chamber 3, into the branch 5 of hot air conduit 1. Thecontinuous supply of highly heated air to the latter is thus maintained when the apparatus is reversed, a relatively small portion of said air being, under these conditions, drawn off through branch 5 to support the combustion of the fuel delivered by burner 7', which is now operating to heat up the checker-work of the regenerator 2. These combustion products from regenerator 2 leave the chamber 3c of said regenerator by the branch pipe 15', and are directed by the valve 15 to the outlet 14.

The volume of air which is forced into the system, under'pressure, by the blower l1 is-maintained at all times in substantially constant proportion to the total amount of low grade fuel, supplied by pipe ll), which is being burned at fthe .several stations not shown,.with the aid' of the air, supplied by pipe 1, that is preheated by said system. 13 is provided with a damper 18 which is operated automatically to increase vor decrease the air Ysupply in proportion to increases or decreases 13,'whereby, in response to variations of demandv on the fuel supply, the regulator 19 produces such movement of damper 18 as to produce corresponding-variations in the flow of air to the system, thus maintaining, in the operation of the system, the desired quantitative ratio of air supply to fuel supply most favorable to proper combustion of said fuel.' A similar automatic pres- Asure regulator 22, having connections 23 and 24,

respectively, to the fuel branch pipe 9- for burners 7 and 7 and to the outlet portion 1li of air duct 13, is' provided for the actuation ofaV damper 25 in said outlet portion'li. A valve' 26 is provided in the fuel branch pipe- 9'to regulate the That is to say, the air supply duct' amount of fuel passing to burner 7 or to burner 7', whichever is operative. The joint regulation of the fuel and heated air admitted to the fuelburning regenerator is obtained by holding substantially constant the pressure prevailing in said 'of the combustion products, would produce a rise of pressure in said fuel-burning regenerator, but for the fact that the regulator 22, acting on damper 25, exerts a corrective influence by balancing the pressure in outlet 14 against the fuel flow pressure in the connection 8. By thus maintaining substantially constant the pressure in the fuel-burning regenerator, the amount Yof heated air entering said regenerator is kept substantially constant and therefore in the proper proportion tothe amount lof fuel admitted by valve 26. In this way the heated air from supply pipe l flows through branch 5 or 5', as the case may be, in the proper proportion 'to givel the desired quantitative ratio of 'air supply to fuel supply rnost favorable to proper combustion at the burner 7 or 7, as the case may be.

In the operation of my improvedsystem, the pipe 1 will be continuously supplied with highly preheated air, this result being obtained by periodic reversals' of damper 16 and valve 17, so that first one andthen the kother of the two regenerators 2v and 2 is used toimpart its heat to the entire supply vof-air blown in under pressure by blower 11,'-meanwhile the other regenerator not so'used being heated up to a high ternperature by the burning therein of fresh fuel, as above described Such periodic reversal of damper 16 and valve 17, to substitute one regenerator for the other as the heating agent for the air supply may, according to ymy invention, be effected manually; however it is preferable to makethe reversals `occur'automatically, inresponse to temperature conditions inthe system, and to this end'the invention contemplates, one -of its aspects, Vthe provision of a thermostat or thermocouple 27 located in the outlet 14 for the combustion products, to secure, periodically, the actuation of a control switch 28, operatively connected, as shown in Fig. l, to both the damper 16 and the valve 17. Assuming the burner 7 to have been made operative for the combustion of fresh fuel in the regenerator 2, while the supply is being forced through Ythe regenerator 2', it will be evident that at the start of such operation, the products of combustion leaving the cold end of regenerator '2 by way of branch l5 and outlet 14 Will be relatively cool, having given up most of their heat to the checlrerworl: chambers 3 and 3a of said regenerator Under these conditions, said products of combustion will have no effect on the thermocouple 27. However, after voperation in this manner for some time, the checkerwork chambers 3 and 3d of regenerator-2 will become hotter and hotter until, finally, they can no longer acquire any further rise in temperature from the ypassage therethrough 'of said'combustion products. Thelattcr will then pass tothe-outlet i4 at al relatively high temperature, sufcient to aifectoperatively the tlfierrnocouple` 27, thereby V'to' `actuate the switch 28 vfor the reversal of damper i6 and valve 17.

By such reversal, as heretofore described, .the burningof fuel is transferred to the, regenerator- 2, andthe highlyy heated regenerator 2 becomes the heating agent for all the airsu-pplied under pressure bythe ,blower 11.. Thereafter, the regenerators 2. and 2 .will interchange. theiriunctionsautomaticallgy at each. operation of the ther.- mocouple27, which indicates approximately 4the absorption of heat by one` or the other of said regeneratorsto its full capacity. y In order tofmaintain a substantially constant temperature for the preheated airsupply in the pipe 1:, the latter is preferably'equippedi with a.- thermostat, or; thermocouple 29, suitably. conf nected, as shown in Fig. 1, to an operatingswitch 30 for a. damper or valve 31 located, in a by-pass duct 32,- directly'cpnnecting; the duct 13` with the pipe 1,.- Inthe, event of anl overheatedair supply in pipe l, the thermocouple 29 isresponse to .temperature procures, through-switch 30, the openingof the normally closed valve or: damper 3-1, allowing some cold air to. be diverted from the duct. 13 to lower the temperature. ofy the preheated airin the pipe l; when the .thermocouple 29 is vno longer affected by the temperaturethe Switch-30 procures thev closure of the valve 31.

YIt will be notedfthat the system of my invention produces continuously a supply of highly preheated air. under positive pressure, and that the temperature and pressure conditions of such preheated air supply can be varied over a considerable range, to adapt them to the. demands. of: thefstation or stations, not shown, to which the preheated air is conveyed by pipe 1.for supporting combustion of the fuel and for obtaining a high llame temperature. It will be understood that. the apparatus herein disclosed for regeneratively preheating this continuous air supply under` pressure is merely illustrative, and that the arrange- Vment and construction of said apparatus issusceptible of wide variation from the present disclosure without departing from the principles and spirit of myinvention. For example, if desired, the regenerators, instead of being separate, could be combined in a single unitary structure, or, under either ,ofy the conditions.v specified (separate or combined) could provide for gaseous flow in only one direction, instead of the up and` down flow required bythe partitionsy 4, 4. a

As illustrative of further variations in the regenerati-ve` air preheating system of my invention, reference is directed to Figs. 3 and 4, showing a system that uses threeregenerators, in any of which fuel may be burned for the purpose of maintaining` a continuoussupply of highly preheated air in a delivery pipe or conduit 41,.-the latter corresponding to the pipe or conduitll ofv Figs. l and 2. nated 42, 42' and-42" respectively, and each'v may oe-ofthe construction shownin Figs.v land- 2, With two chambers 3 and 3a separated from. each other by a partition or Wall 4. Also, the same'as in Figs. l` and 2,` the delivery pipe 41 for preheated air has branches 5, 5 and 5 that communicate respectively, las shownat 66" and'f6",

with the several regenerator` chambers 3',..3, 3

near-the upper ends of the latter, and these connections66 and 6" are disposed the fuelgburners-7, '7' and 7" respectively, each adapted, at the-proper time, to be'supplied with fuel through suitable branches 8, 8' vand 8", leading from the. fuel pipe 9', the latter being connected, the same asin Figs. 1 and 2,-to a fuel supply pipe 10'.

All the air that is supplied to the system shown inFigs. 3 and 4 is handled by a blower 11.', which The-three regenerators are desig is ,.contmuouslyrdriven. asby a motor 12', and which l.delivers-said'.air. under. pressure to a duct 43,.,eorrespondi-ng` substantially in function vto the duct .13 of Figs. 1 and 2. .This duct 43 provides, three outlets 44, 44' and 44" tothe atmiosphere,A onefor each of the three regeneratorsreach of the 4latter having its chamber 43a connected. to the appropriate` outlet by a branch pipe,-the.=three branch pipes being. designated, respectivelm, 45' and 45". vAt the juncture of each. said` branch` pipe, with the outlet `from its reglenerator is disposeda valve. or damper 46, adapted in one position (when fuel is beingburned in. the. associated regenerator), toy direct the ,combustion products in.to,.tlfie outlet-and adapted in itsother position (when the associated regeneratar..i.sv beinglemployed forthe, heating of air.) to direct Aair from the duct 43 into the chamber, 3cr of. said regenerator.

Asshown inFig. 4,v suitable linkage 46a is pro vided, .to. connect .each of the. three valves or damperst Ywith an associated valve 47 in the fuel supply. line of the. same regenerator; by this linkage when a valve 46, for example,is in the position shown in Fig'. 4, the corresponding fuel valve 47 is open, to permit. the passage of fuel-to be burned. .to the associated regenerator,but

when the valve 46 is shiftedto its other position,

for the admission of air to said regenerator,.then the valve 47 will be moved to closed position, shutting off the fuel supply to that particular regenerator.

.Substantially the .same means as shown in Figs. 1 and- 2, for maintaining the.l correct proportion of the air supply to. the total amount of fuel being burned, is provided in the arrange# ment of Figs. 3. and 4,-there being a damper 18' in the air supply duct 43, which is suitably Connected'to a pressure regulator 19', the latter, as shown, having connections20 and'2l, respectively,.to the fuel pipe l0' andto the air duct 43', whereby, in response to variations of demand onI the. fuel'` supply, the. regulator 19' produces such movementvof damper 18" as to produce corresponding: variations in the flow of air to the system. Also, associated. with each outlet 44, 44' or 44." from each..regenerator, is a similar automatic pressure regulator 22', having connections 23' and 24,', respectively, to the fuel inlet branch and tothe Waste gas outlet of the associated regenerator; this regulator 22', in eachV instance, actuates a damper 25' in the corresponding outlet 44, 44 or 44", as the case may be. Ina-smuchas the fuel inlet toy each regenerator has a fuelregulating valve 26', to adjust vthe amount ofV fuel .passing to its burner, itwill be clear that the lposition ofdamper. 25', controlling the outflow of the product'sresulting from the combustion-in the associated regenerator, is automatically determined by the associatedregulator` 22', in such manner that .the volume of combustion products passing said damper 25 and exhausting to the. atmosphere is directly ,proportionalv tol the amount of fuel admitted. by valve 26' to the associated regenerator. hence the preheated; air which provides the greaterportion of the volume oi said combustion products is drawn .from the air supply main 4l in the proper proportion `to give the desired quantitative ratio of air supply. to fuel supplymost. favorableto proper combustion ofthe fuel being burnedv in the associated regenerator.

Inl the operation of' the systemv shown in Figs. 3. and 4,l 4one .ofnthe regenerators, such as 42, may be employed'. for the burning of fresh fuel,

while the other two regenerators 42 and 42", having been previously heated, may be employed for raising the temperature of the 'air that is being continuously supplied to the system. Or, if desired, fuel may be burned in two regenerators, While air is being heated in only one of them. In any case, the change in the operating function of any regenerator (from fuel burning to air heating, or vice versa) may be effected by periodic shifting of its associated damper 46 and fuel supply valve 47; this shifting can be effected manually, or, if desired, automatically. In the latter case, each regenerator outlet 44 or 44", as the case may be, is equipped with a thermostat or thermocouple 27', adapted to secure periodically the actuation of a control switch 28', that is operatively connected, as shown in 4, to the linkage that connects the associated damper 46 and valve 47. Assuming the burner 7 of regenerwtor .42 to have been rnade operative for the combustion of fresh fuel in said regenerator, while +214 air supply being forced through the other two regeneiatorsY 42 and 42, it will be evident that at the start of such combustion in the regenerator 42, the products of combustion leaving by way of draven and outlet 44 will be relatively cool,

iven up most of their heat the che chambers 3 and of said regenerator der these conditions, said roducts of ooinbustion will have no eifeot on the tl 27. 1lowever, after operation in manner for some time, the combustion roducts will pass to the outlelL 44 at a relatively t l pressure to the duct 43.

The system shown in Figs. 3 and 4 may, like the system shown in Figs. 1 and 2, divert a portion of the air from cold ductl 43 to hot ai duct 41, without passing it through any of t regenerators 42, 42 or 42". En the case of Figs. 3 and 4 however, this air so diverted receive heat froin sources other than said regenerators,

s, for instance, by connecting the duct 43 to a recuperator or other equivalent device 4S, wherein said cold air is circulated in coi itercurrent to waste hot gases coming, for

he furnaces or other fuel burning st are served by the system. Said so heated in the device 4S then passes by way of p' 49 to the hot air duct 41, to augment the sup of hot furnished by whichever of the reg ators 42, 42 and are then bei' g used for air heatof damper 50, permitting ingres volume to duct 41 of air that is less highly heated than the air supplied by the regenerators; on the other hand, if the temperature in duct 4l falls too low, the thermocouple 29 will close,

or partly close, the damper 5l), thereby causing a greater portion of the air supply from blower ll to pass through one or more or" the regenerators 42, 42 and 42".

In both forms of the invention, as above described, it should be noted that when a regenerator is being used for the burning of fuel, it is receiving air from the same source as that which supplies the regenerator or regenerators used for the of said ain-notwithstanding the factA that this fuel-burning regenerator is not directly connected with the pipe or duct (13 or 43) into which the entire air supply is blown. rEhe fuel burning regenerator receives such air only after it has passed through the checkerwork of one 'of the direct-connected regenerators. It should also be noted that the pressure maintained in such direct-connected regenerator or regenerators will be substantially that maintained in the hot ir delivery duct (1 or 41) whereas the presrc ained the fuel burning regenerator e ioiver the aforesaid pressure, by such mount as is necessary to cause a flow from t air to said fuel burning regenerator cient to support the combustion-of the fusil-seing burned in said fuel burning regenerator. It will readily be seen that this flow will be materially checked by creation of pressure, due to expansion of the gases of combustion resultfro the chosen rate of fuel consumption in last-named regenerator, and that therefore adeqi .te provision must be made to relieve this pr ssure through an outlet or stack (14 or 44) with a regulatable opening; by such regulation of the operig, the pressure in the fuel burning regenera can be made less than that in the air heating regenerator or regenerators, in order to flow of air from the latter to the former.

I clairi:

1. ln the regenerative preheating of air, the proveinent which consists in burning fresh fuel to provide, in regenerators used alternately the of a cci nuous air supply under pressure, the heat for st eh preheating, supporting combu .on of said fuel by a portion of the supply so ted, and maintaining by control the combos on. products leaving such Wfuelburning regenerator a substantially constant pressure in such regenerator.

2. In the regen, ative preheating of air, the roveinent which consists in burning fresh fuel provide, in regenerators used alternately for t' of a continuous air supply under sure, the heat for such preheating, supportthe combustion of sail fuel by a portion of the air supply so heated, and maintaining, by control of the combustion products leaving such fuel-burning between the volumes of fuel and air supplied thereto.

S. In a regenerative air-preheating system, the combination. with a plurality of regenerator chambers passages used alternately for the passage of and the burning of fuel,-of'means for supplying under pressure continuously to system, means for diverting a portion of the pressure aisupply, following its heating, to vid the combustion of the fuel so burned in the system, pressure regulated means operative on the .outgoing combustion products for maintaining a predetermined ratio between the volune of air so diverted and the amount of fuel so burned.

4L In a regenerative air-preheating system., the

regenerator, a predetermined ratiol combination with a plurality of regenerator chambers or passages used alternately for the passage of air and the burning of fuel, of means for supplying air under pressure continuously vto said system, means for diverting a portion of the pressure rair supply, following its heating, to aid the combustion of the fuel so burned in thei'system, and pressure-regulated means operative ron the combustion products exhausted from said system for maintaining a predetermined ratio between the volume'of air s'o diverted and the amount of fuel so burned.`

5. In a systemfor the preheating of air, to produce high flame Vtemperature from the combustion of fuel in the presence of said air, the combination with means for supplying air under pressure continuously to said system, of pressureregulated means for automatically maintaining a predetermined ratio between the volume of such pressure air supply and the amount of fuel being burned with the aid of the heated air delivered by said system.

6. A system for the regenerative preheating of air, to produce high flame temperatures from the combustion of fuel in the presence of said air, comprising a plurality of regenerators, means for supplying air under pressure continuously to said system, means for directing a portion of said air supply through certain of said regenerators while burning fresh fuel in other of said regenerators, an oiftake conduit common to all of said regenerators for delivering the preheated air emerging from the first-mentioned regenerators to the station or stations where fuel is to be burned, and to the fuel-burning regenerator or regenerators, and meansfor diverting directly to said offtake conduit, without passage through said regenerators, another portion of the air supplied under pressure to said system.

'7. A system for the regenerative preheating of air, to produce high flame temperatures from the combustion of fuel in the presence of said air, comprising a plurality of regenerators, means for supplying air under pressure continuously to said system, means for directing a portion of said air supply through certain of said regenerators while burning fresh fuel in other of said regenerators, an oiftake conduit common to all of said regenerators for delivering the preheated air emerging from the first-mentioned regenerators to the station or stations Where fuel is to be burned, and to the fuel-burning regenerator or regenerators, and means for utilizing the combustion products from the fuel-burning station or stations for heating another portion of the air supplied under pressure to said system, prior to the delivery of said last-mentoned portion to said oiftake conduit.

8. A system for the regenerative preheating of air, 'to produce high. flame temperatures from the combustion of fuel in the presence of said air, comprising a plurality of regenerators,V means for directing a continuous supply of air under pressure to certain of said regenerators while burning fresh fuel in other of said regenerators in the presence of heated air delivered by said firstmentioned regenerators, and means for maintaining a lower pressure in said fuel-burning regenerator or regenerators than in said regenera- 'tor or regenerators used for the heating of said air.

9. A system for the regenerative preheating of air, to produce high flame temperatures from the combustion of fuel in the presence of said air, comprising a plurality of regenerators, means for directing a continuous supply of airv under pressure tov certain of said regenerators while burning fresh fuel in other of said regeneratorsin the presence of heated air delivered by said first-mentioned regenerators, means for maintaining a lower pressure in said fuel-burningA regenerator or regenerators than in said regenerator or regenerators used for they heating of said air, and means for interchanging the fuel-burning and air-heating functions of said regenerators.

' l0. A system for the regenerative preheatingof air, to produce high flame temperatures from the combustion of fuel in the presence of said air, comprising a plurality of regenerators, means for blowing a continuous supply of air under pressure through certain of said regenerators while burning fresh fuel in other of said regenerators in the presence of heated air delivered by said first-mentioned regenerators, and means responsive to overheating of the air in said system for diverting to the air outlet thereof a portion of the pressure air supply, before the latter is heated.

l1. A system for the regenerative preheating of air, to produce high flame temperatures from the combustion of fuel in the presence of said air, comprising a plurality of regenerators, means for blowing a continuous supply of air under pressure through certain of said regenerators While burning fresh fuel in other of said regenerators in the presence of heated air delivered by said first-mentioned regenerators, means responsive to overheating of the air in said system for diverting to the air outlet thereof a portion of the pressure air supply, before the latter is heated, and means for maintaining a lower pressure in said fuel-burning regenerator or regenerators than in said regenerator or regenerators used for the heating of said air.

12. A system for the regenerative preheating of air, to produce high iiame temperatures from the combustion of fuel in the presence of said air, comprising a pair of regenerators, means for blowing a continuous supply of air under pressure through one of said regenerators, while burning fresh fuel in the other of said regenerators in the presence of heated air delivered by said firstmentioned regenerator, means for interchanging the fuel-burning and air-heating functions of said regenerators, and means for maintaining a pressure diiferential between said regenerators, with the higher pressure always in the regenerator wherein the air supply is being heated.

13. A system for the regenerative preheating of air, to produce high iiame temperatures from the combustion of fuel in the presence of said air, comprising a plurality of regenerators, means for blowing a continuous supply of air under pressure through certain of said regenerators while burning fresh fuel in the other of said regenerators in the presence of heated air delivered by the first-mentioned regenerator or regenerators, means for reversing said system to interchange the fuel-burning and air-heating functions of said regenerators, and means operative on the combustion products discharged by the fuelburning regenerator or regenerators for maintaining a pressure differential between the fuelburning regenerator or regenerators and the airheating regenerator or regenerators.

14. A system for the regenerative preheating of air, to produce high flame temperatures fromr the combustion of fuel in the presence of said air, comprising a plurality of regenerators, means for blowing a continuous supply of air under pressure through certain of said regenerators While burning fresh fuel in the other of said regenerators in the presence of heated air delivered by said first-mentioned regenerators, and means responsive to rise in temperature of the combustion products delivered by the fuel-burning regenerator or regenerators for reversing said system, to interchange the fuel-burning and airheating functions of said regenerators.

15. A system for the regenerative preheating of air, to produce high flame temperatures from the combustion of fuel in the presence of said air, comprising a plurality of regenerators, means that is being burned in the presence of the heated air supplied by said system.

GEORGE H. IsLEY. 

